The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Dec. 21, 1999
Filed:
Apr. 22, 1998
Zf Friedrichshafen AG, Friedrichshafen, DE;
Abstract
In a displacement pump for pumping pressure medium out of a container to a consumer, in particular a servo-assisted steering system for motor vehicles, a pump package (2) is inserted into the interior of a housing (1). The pump package (2) comprises a rotor (3), a cam ring (4) and a plurality of operating rods (5). Between the cam ring (4) and the rotor (3), work chambers divided by the operating rods (5) are formed, which are bounded in the axial direction by control plates (8, 9). A bypass flow limiting to valve (11) is used to regulate an effective flow. A throttle (12) of the bypass flow limiting valve (11) is formed by at least one bore. The throttle (12) is embodied in a throttle insert (13), which to adjust a characteristic effective flow curve can be mounted in various positions between a pressure chamber of the pump and the bypass flow limiting valve (11). To that end, the throttle insert (13) is integrated with a control plate (9). In addition, at least two bores (14, 15) are provided in the throttle insert (13), which discharge into a pressure kidney (10a) disposed in the control plate (9). A control plate is a precision part, so that the flow conditions and thus the characteristic governing curves can be reproduced very accurately. As a result of the mutual influence of the two throttle bores, the governing tolerance is not sensitive to minor errors in the rotary position of the throttle insert.